If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Main content
Current time:0:00Total duration:2:03

Video transcript

match these angles with their measures there should be one angle in each category of 30 degrees six degrees 90 degrees and 180 degrees so there's a few that are very easy to spot out this angle right over here it's it makes a complete line so this is clearly 180 degrees so this one's 180 degrees the other one that might jump out at you is this one right over here this is clearly a right angle or a 90-degree angle right over here so this is 90 degrees and so we have to think which of these is 30 and which is 60 degrees well just by comparing it that way you know that the one that opens out more is going to be 60 degrees and the one that opens out less is going to be 30 degrees and you can see that this the opening here is half the size of the opening right over here so it makes sense that this is 30 this is 60 and also makes sense that this angle is one-third the measure of this angle right over here that this is 90 degrees and then if you were to double this then this this part of the angle would go all the way out and you would get to 180 degrees so let's check our answer make sure we we actually got this one right let's do one more just for fun which of these angles has a measure of 60 degrees so there's a couple that we can immediately rule out this angle here is clearly more than 90 degrees it's an obtuse angle this angle here is 180 degrees so we're gonna have to pick between these two and we can assume that these are all at scale so if we know that a right angle would have this line straight up and down this looks like it's two-thirds of the way there so I would go with this one right over there now you might say well what about this one well this one looks like it's about a third of a right angle if we were to do two thirds then three thirds it looks like we would get to a right angle so this one looks much closer to 30 degrees so which of these angles has a measure of 60 that one right over there you can immediately rule out that one and that one and then these take a little bit closer inspection